Caleb from Brownells builds what he calls the ultimate pistol caliber carbine (PCC) using the CMMG radial delayed blowback system. Unlike traditional direct blowback AR-15 9mm builds, this setup uses lighter parts, reduced recoil, and improved reliability. Follow along as he walks through every part of the build including the lower, upper, barrel, magazines, muzzle device, and accessories, then completes the assembly with a suppressor-ready setup.
Chapters:
00:00 – Intro to the Ultimate PCC Build
00:18 – Radial Delayed Blowback vs Direct Blowback
02:08 – CMMG Radial Delayed Bolt and Barrel Design
04:20 – Buffer and Recoil System Setup
04:49 – AR-15 Lower Parts and Magazines
07:19 – AR-15 Upper Receiver and Barrel Installation
08:34 – Handguard and Barrel Nut Setup
10:25 – Installing the Muzzle Device
11:48 – Handguard and Suppressor Fitment
14:37 – Optic and Accessory Setup
15:24 – Installing Vertical Grip and Hand Stop
16:39 – Rail Covers for Comfort and Grip
17:32 – Charging Handle and BCG Installation
18:32 – Upper and Lower Assembly
18:48 – Suppressor Installation
19:02 – Final Thoughts and Wrap Up
This PCC seems perfect for my needs. Can Brownells publish out a parts list for use in ordering/building this gun? Thanks for a great video!
Is there a build list?
I just made something pretty similar to this, but I used the fixed ejector version and put a kynshot of it. Just finished it the other day so haven’t had a chance to take it to the range yet.
Watching this video traveling. In Commie-fornia. Keep looking over my shoulder to see if they are running to arrest me just for watching this. Sadly, that ain’t too far from the truth here.
Heard your a gun company who sucks! Mags are 30rds not 15 ladies! Get off your knees for the government you cowards!
I just finished an AR-9 build that I've been working on for several months. I used information contained on Blowback9's website and YouTube channel. Doug, the proprietor of Blowback9, is the saint of the 9mm AR. He knows his stuff, and his website contains free info on various parts and setups. It's worth a look for sure if you're building a 9mm PCC. I used his suggested "gentle recoil system" to amazing effect. It consists of a hydraulic buffer, an extended length buffer tube, spacer weights and a flat wire carbine spring. First trip to the range this past weekend with my little 9mm varmint went way better than I expected. 200+ rounds with no malfunctions, and it shoots butter smooth with little to no recoil. The hydraulic buffer creates a delay in the bolt cycle and eliminated bolt bounce. Combining it with a muzzle brake took almost all the muzzle rise out of the gun. Granted, it is heavier than a "true" delayed system, but it's also easier to build and, in most cases, less expensive. I would urge anyone who has a desire to put together an AR platform PCC, especially a 9mm, to check out Blowback9's information; Doug is not monetized in any way (and has no desire to be) and makes sure his information remains open for everyone to access and use. He also has build lists for various setups that have been sent to him for review and evaluation that are also open for folks to use and reference.
Is there a parts list?
No rocket on the muzzle device?
Lmao i can ONLY use the bigger hole
Should try the MEAN Arms upper with the Unrivaled buffer designed for it.
I wouldn't throw him out of bed for eating crackers…
Jesus Christ is this guy just winging this whole video lol.
For any of you less experienced watchers, Caleb forgot to mention:
DON'T put a stock or vertical grip on any rifle if the barrel is less than 16 inches, unless you registered it as an SBR, or want to end up in federal prison 🤣
The whole PCC fad eludes me. Why use an underpowered 9mm round when one could use 300 BLK for the same size, weight, and ergonomics? The 300 AAC was engineered PRECISELY because of the poor terminal performance of the 9. And switching to 300 BLK supersonics vastly increases the range and power. The only benefit from 9mm is ammo cost and availability.
If you’re going to drop a grand, why build a toy when you could build a weapon with vastly improved lethality for the same size, weight, and ergos?
Really dig the build. I built something similar cmmg upper on a lower with an A5 and kak spring loaded 0 buffer
"Use the bigger hole" words to live by…
RAdial is a good move. Blowback is a huge problem.
Mat9 looks better
Do they make Di 9mm ARS
@11:14
I wanna know who makes that upper receiver vice block
Very nice. I have the PCC build next on my list although it seems I can use the two AR-15 lowers I have. Thanks.
I want to have an ar9 build, but I’ve always wanted one that takes glock or scorpion mags. Those mean mags seem too proprietary.
Great build 🤙🏽🤩🙌🏼
All these years and you still can’t show a close-up, your camera set up sucks
Would love to see a full build video on a suppressed 300blk!. Especially one that has a folding stock
🇺🇸
Nice!!!!
Meh, I'm good with my new Kuna.
I built a 9mm PCC on a budget in 2018, just for giggles. It's straight blowback, with a very heavy buffer and a stiff recoil spring to control it. The recoil isn't bad, but it's pretty heavy for such a small gun. Also, it's fun to shoot!
Do you?
Guys carry all the parts to put this gun together
Another good video, could use better lighting and a close-up of what what your explaining.
Good looking sbr PCC… I have about 5 of those sledgehammer charging handles… Met the breek guys at canyon and that charging handle is fantastic for supressed guns!
The only problem with the CMMG RDB system is that it will go through ejector springs quicker than a normal AR will. I have about 6.5k through mine, mostly suppressed and what C3Junkie calls the ARS (A5 tube, flat spring, and RB5007 buffer). I have had to change my ejector springs out 6 times. The system is great but I'll be switching to the fixed ejector soon and trashing my other BCG. For the casual shooter it probably won't matter but for anyone who competes or shoots a lot it will become an annoynace fast.
It's an obvious improvement and I bet CMMG will eventually only offer it. I hope they start coming out with bolts with different angled cuts so we can better tune the system for suppressed use.
well, that was a nice build.
@brownells, did the T0 buffer end up working out or did you have to switch it?
Glock magazine compatibility? Otherwise Foxtrot Mike at 12k and counting has my money.
You built a nice SBR, better get that registered or you’re going to have ATF headaches.